EP3684982A1

EP3684982A1 - Reusable offshore installation template and use thereof

Info

Publication number: EP3684982A1
Application number: EP18778864.1A
Authority: EP
Inventors: Ben Edgard CASIER; Dries Joris Lammens
Original assignee: Jan De Nul Nv
Current assignee: Jan De Nul Nv
Priority date: 2017-09-22
Filing date: 2018-09-20
Publication date: 2020-07-29
Anticipated expiration: 2038-09-20
Also published as: TW201920813A; EP3684982C0; EP3684982B1; WO2019057827A1; TWI770281B; BE1025255B1; ES2977603T3

Abstract

The present invention relates to a reusable offshore installation template for the installation of offshore wind turbine foundations, in particular monopiles. The template comprises a sleeve 100 adapted to receive the monopile and guide it in the sleeve direction through the sleeve, and a support assembly (300) comprising a base (310) defining a landing surface and a support frame (320) extending from the base. The installation template is adapted to reorient the sleeve direction S relative to the landing plane of the base based on a force applied to the sleeve.

Description

Reusable offshore installation template and use thereof

Field of the Invention

The present invention relates to a reusable offshore installation template for installing an offshore wind turbine foundation, in particular a monopile, in an underwater ground formation. The present invention further relates to a method for installing an offshore foundation, in particular a monopile, in an underwater ground formation by means of an offshore installation template.

Background

Such templates are known, e.g. from EP 2,309,063 and WO 2013/043055. These prior art documents disclose pre-piling templates for installing a jacket foundation with the aid of multiple sleeves along the circumference of a structure connecting the sleeves. However, such templates are not designed for installing monopiles and are not suitable for installing a monopile in an odd or locally undulated seabed of the underwater ground formation. The odd or locally undulated shape of the seabed may cause the template to be supported at an undesirable angle relative to a horizontal plane, which may result in the monopile being installed in an undesirable, non- vertical orientation.

A template, as known from US 8,672,587, comprises a base and a sleeve consisting of two substantially semi-cylindrical sleeved parts, as described in WO 99/11872. Each sleeved part is connected to the base by means of a pair of positioning members, each positioning member consisting of a length-adjustable element and a joint assembly. By adjusting the length of one pair of positioning members, the sleeve will pivot around a pivot axis defined between the two pair of positioning members, and it is possible to tilt the sleeve.

A known problem with the above templates is that when inserting the offshore wind turbine foundation into an underwater sleeve of a template, the foundation can be influenced by water currents and/or by vessel movements when installing from a floating vessel. The monopile foundation can move as a result of the above forces and make the insertion of the monopile more difficult or even prevent, or lead to an installation in an undesirable, non- vertical direction. In addition, undesired forces can also be imposed on the floating vessel in this way. Object of the Invention

An object of the invention is to provide an offshore installation template that solves the above mentioned problem. Furthermore, it is desired to allow installation of a monopile in a predetermined (vertical) orientation with respect to the template base.

Summary of the Invention

Accordingly, in a first aspect of the present invention, there is provided an offshore installation template for installing a monopile in an underwater ground formation. The template comprising a sleeve with a sleeve passage extending through the sleeve in a sleeve direction, said sleeve passage being adapted to receive the monopile and to pass the monopile through the sleeve in the sleeve direction, and a support assembly comprising a base defining a landing surface and a support frame extending from the base for supporting the sleeve.

The installation template further comprises positioning members for reorient the sleeve direction relative to the landing surface, said positioning members being adapted to reorient the sleeve direction relative to the landing surface based on a force applied to the sleeve, e.g. based on the magnitude or a (lateral) component of that force. In this manner, it is possible to install monopiles from an offshore installation vessel in a desired predetermined (vertical) orientation despite relatively large forces applied to, and relatively large pressure exerted on, the sleeve during installation. The relatively large force applied to the sleeve during installation may be the result of fluctuating or dynamic forces, i.e. forces changing over time, and is larger than a relatively low force applied to the sleeve determined before introducing the monopile into the sleeve.

According to a preferred embodiment, the present invention relates to the installation template as described above, wherein the positioning members are adapted to reorient the sleeve direction relative to the landing surface when passing a threshold value of the force applied to the sleeve, i.e. exceeding the threshold or falling below the threshold. In this manner, installation template is adapted to perform corrective actions to ensure the installation direction of the monopile when a relatively large force is or has been applied to the sleeve. According to an embodiment, the present invention relates to the installation template as described above, wherein the positioning members are adapted to reorient the sleeve direction relative to the landing surface in the direction of the force acting on the sleeve when the threshold is exceeded.

According to another embodiment, the present invention relates to the installation template as described above, wherein the positioning members are adapted to reorient the sleeve direction relative to the landing surface toward a vertical installation direction with respect to the environment, in particular an offshore environment, when the force applied to the sleeve falls below the threshold or a second threshold that is less than the threshold, and preferably maintained below that threshold during a predetermined time.

In an embodiment, the present invention relates to the installation template as described above, wherein the positioning members extend between the support frame of the support assembly and the sleeve, preferably at least at least three positioning members are rotationally symmetrical in an orientation plane. This makes it possible to efficiently orientate the sleeve direction. In the preferred embodiment, the risk of failure is also reduced by the presence of at least two positioning members which can orient the sleeve in a particular manner. Moreover, the monopile may be installed vertically in an underwater ground formation independent of the shape of the seabed.

In further embodiment, the present invention relates to the installation template as described above, wherein the positioning members are hydraulic cylinders arranged to adapt its pressure level based on the force applied to the sleeve, in particular upon passing a predetermined threshold value. In particular, the positioning members are hydraulic cylinders which are adapted to be pressure released by means of an overpressure valve/hose rupture valve, possibly pilot controlled, if the pressure in the cylinder becomes too high as a result of a force exerted on the sleeve. This has the advantage that a damped movement of the sleeve is allowed similar to a movement in a damped mass-spring system.

In other embodiments, the present invention relates to the installation template as described above, wherein the installation template comprises a sensor, said sensor being adapted to determine a parameter related to a force exerted on the sleeve. In this embodiment, the force exerted on the sleeve may be determined in a simple manner and the sleeve direction S may be reoriented by the template on the basis of the parameter. Optionally, the installation template further comprises separate control means to control the positioning members using a control signal based on a sensor signal of the sensor.

According to a second aspect of the invention, which may occur in combination with the other aspects and embodiments of the invention described herein, there is provided an offshore installation template in which the sleeve and the support assembly together comprise spherical hinge elements which together define a ball and a socket of a ball joint and allow a rotation of the sleeve with respect to the support assembly around a rotation point.

In this way the orientation of the sleeve may be changed with respect to the base, for example for v ertical installation on an uneven or locally undulated seabed of the underwater ground formation. In addition, this configuration has the advantage that the sleeve may be efficiently oriented. Furthermore, because the ball can consist of several hinge surfaces, it is also possible for the sleeve to extend through the ball hinge. And this has the advantage that the ball hinge may be formed compactly.

According to an embodiment, the present invention relates to the installation template as described above, wherein the socket is formed by hinge elements provided on the sleeve and the ball is formed by hinge elements provided on the support assembly.

According to an embodiment, the present invention relates to the installation template as described above, wherein said spherical hinge elements of the sleeve are formed by a plurality of hinge arms which are rotationally symmetrically provided on an outer surface of the sleeve, and said spherical hinge members of the support assembly are formed by a plurality of spherical surfaces that are rotationally symmetrically provided on the base of the support assembly.

According to a further embodiment, the rotation point of the spherical hinge coincides with a point of a passage opening of the base, said passage opening being provided for the passage of the monopile into the underwater ground formation. As a result, the orientation of the sleeve direction S will always comprise the point of the base. This has the advantage that when changing the orientation of the sleeve, a target position determined by the point is maintained. For example, if the template orientates the sleeve such that a force applied to the sleeve is damped, then the sleeve remains arranged to guide a monopile to the correct target position. According to a third aspect of the invention, which may occur in combination with the other aspects and embodiments of the invention described herein, there is provided an offshore installation template wherein the support assembly comprises at least one template foot for stabilizing the position of the support assembly relative to the seabed of the underwater ground formation. When the seabed is not level, it is possible to get a grip on the seabed with the help of a template foot. In addition, it is possible to preload the template with the aid of at least one template foot such that a predetermined surface pressure is exerted on the seabed for a certain time.

According to a fourth aspect of the invention, which may occur in combination with the other aspects and embodiments of the invention described herein, there is provided an offshore installation template wherein the dimension of the sleeve in the sleeve direction is adjustable.

In this manner, it is possible, for example, to adjust the height of the sleeve so that it always extends a sufficient length above the water surface in an offshore env ironment. This has the advantage that the template is visible from, an offshore installation vessel, for example during the insertion of the monopile into the template, in addition, a sleeve extending abov e the water surface will also have an advantageous effect on the sound propagation during the hammering of the monopile in the soil.

According to an embodiment, the present invention relates to the installation template as described above, wherein the sleeve is modularly arranged by means of a main part and a top part connected thereto. In this embodiment, the size o the sleeve can be adjusted in a simple manner. According to a further embodiment, the top part is connected to the main part by means of at least one modular part. This embodiment determines in a simple manner a number of discrete dimensions in which the sleeve is adjustable. An additional advantage is that these modular sleeve parts are easy to store because they may be stacked together.

According to a fifth aspect of the invention, which may occur in combination with the other aspects and embodiments of the invention described herein, there is provided a support assembly for an installation template comprising positioning members for reorienting a sleeve direction of a sleeve relative to a landing surface of the support assembly, said positioning members being adapted to reorient the sleeve direction relative to the landing surface based on a force applied to the sleeve. A sixth aspect of the invention, which may occur in combination with the other aspects and embodiments of the invention described herein, provides for the use of an offshore installation template according to the invention in an offshore environment comprising a ground formation with a seabed and a water formation with a water surface. The base of the support assembly is located on the seabed of the ground formation, and the sleeve extends through the water surface of the water formation.

Because the sleeve extends above the water surface, the monopile does not begin to oscillate through the currents and the waves. This makes it easier to insert the monopile in the sleeve. In addition, it is also an advantageous configuration to prevent the propagating of sound waves in the water formation. In particular, the sleeve of an installation template according to the invention may be further provided with sound- absorbing means in order to more efficiently counteract the propagation of the sound waves. The sound-absorbing means may be, for example, a coating of the sleeve, harmonic resonators, air bubble screens, etc.

A seventh aspect of the invention, which may occur in combination with the other aspects and embodiments of the invention described herein, provides for a method for installing a monopile in an underwater ground formation by means of an installation template, comprising the steps of providing a base of the installation template on a seabed of the underwater ground formation, introducing the monopile into a sleeve passage extending through a sleeve of the installation template, and, preferably when a threshold value of a force applied to the sleeve is passed, reorienting a sleeve direction relative to a landing surface of the base adjoining the seabed based on a force applied to the sleeve.

According to an embodiment, the present invention relates to the method as described above, comprising, prior to the step of introducing the monopile, the step of orienting the sleeve direction relative to the landing surface by means of positioning members.

According to a further embodiment, the present invention relates to the method as described above, by means of an offshore installation template according to the invention. Brief description of Drawings

The invention will be explained in more detail below with reference to drawings in which illustrative embodiments thereof are shown. They are intended exclusively for illustrative purposes and not to restrict the inventive concept, which is defined by the appended claims.

Figure 1 shows in a perspective view a simplified representation of a reusable offshore installation template according to an embodiment of the present invention; Fig. 2 shows in side view the template shown in Fig. 1 in a storage position;

Figure 3 is a side view of the template shown in Figure 1 in a "pre-load" position;

Figure 4 shows the template shown in Figure 1 in use on the seabed of an underwater ground formation; and

Figures 5A-D show the template shown in the previous figures in various steps of a method for installing a monopile in an offshore environment. Detailed Description of Embodiments

Figures 1-3 show the template 100 comprising a sleeve 200 and a support assembly 300. Figure 2 shows the template in a storage position for storing the template out of service. Figure 3 shows the template in a preloading position for preloading an underwater ground formation 500.

The sleeve 200 has a generally hollow cylindrical shape around a sleeve direction

S, wherein the sleeve 200 comprises a sleeve passage for passing a monopile 400. In this sleeve passage there may be clamping and/or guide means present to help install the monopile 400. The sleeve 200 further comprises a main part 210, a top part 230 and several modular sleeve parts 220; 221, 222, 223 which connect the top part 230 to the main part 210 in a non-destructive detachable manner, for instance using bolts and nuts. The main part 210 is provided with a plurality of hinge arms 240 on an outer surface of the sleeve, said hinge arms 240 defining the socket of a ball joint, or at least a part thereof.

The support assembly 300 has a substantially cylindrical frame 320 provided around a support direction O with an annular base 310 at the proximal end of the support frame 320. The base 310 defines a landing surface which, during use, rests on the seabed of an underwater ground formation. The support assembly 300 further comprises a plurality of feet 350 for supporting and stabilizing the template 100. The shown embodiment is equipped with four feet 351, 352, 353, 354 arranged rotationally symmetrically around the support direction O.

The support assembly 300 also includes positioning members 330 in the form of hydraulic cylinders extending between the support frame 320 of the support assembly 300 and the outer surface of the sleeve 200. The positioning members 330 define a positioning plane perpendicular to the direction of support O.

The positioning members 330 arc arranged to orient the sleeve direct ion S relative to the landing surface of the base 310. The embodiment shown comprises four positioning members 331, 332, 333, 334 which are arranged rotationally symmetrically around the supporting direction O in the orientation plane. As a result, t e risk of failure is reduced by the presence of at least two positioning members that can bring the sleeve into an adjusted orientation. In particular, the positioning members 330 are directly connected to the sleeve 200.

The support assembly 300 further includes spherical hinge surfaces 340, the spherical surfaces 340 defining the bail of the ball joint, or at least a part thereof. The embodiment shown comprises four spherical surfaces 341, 342, 343, 344 which are arranged rotationally symmetrically around the supporting direction (). In particular, the positioning members 330 and the spherical hinge surfaces 340 are arranged alternately in a circumferential direction of the template 100.

Figure 4 shows the template in a lowered posit ion on a seabed 510 of the ground formation 500. The landing surface of the base 310 is supported by the seabed 510. The feet 350 engage the seabed 5 10 with the aid of hydraulic cylinders to further support the template 100. Optionally, one or more feet 350 can also be used to preload the underwater ground formation 500.

In the offshore environment with a horizontally ev en seabed 10 the sleeve direction S will coincide with the support direction O to be correctly aligned w ith a vertical installation direction V determined by the environment, more specifically the water surface 610 of the water formation 600. The sleev e 200 has a predetermined height in the vertical installation direction V such that in the lowered position the top part 230 is at least partly above the water surface 610. Because the template is sticking out of the water. the monopile will not start oscillating due to the currents and the waves. This makes the insertion of the monopile into the sleeve easier.

Figures 5A-D show the template 100 shown in Figures 1-3 during use in various steps of a method for installing a monopile 400, for example from a heavy lifting vessel (e.g. a crane vessel), in an underwater ground formation 500.

Figure 5 A shows the template 1 00, after lowering the template 100 from an ov erboard posit ion with respect to the heavy lifting vessel, in a lowered position on an horizontally unev en seabed 5 10 o the ground format ion 500. In this lowered position, the sleeve direction S coincides with the supporting direction O that is almost perpendicular to the seabed.

Figure 5B shows the template after orient ing the sleeve 200 relat iv e to the landing surface of the base 310. In order to correctly align the sleeve direction S, the sleeve is oriented by means of the positioning members 330 such that the sleeve direction S coincides with the vertical installation direction V. This makes it possible to install a monopile 400 in a vertical direction despite the horizontally uneven seabed 510.

Figure 5C shows the template 100 during the step of introducing the monopile 400 into the oriented sleev e 200 shown in Figure 5B. The monopile 400 is lowered from an ov erboard posit ion to the ground formation 500, the monopile 400 is aligned with the sleeve direct ion S to install the monopile 400 through the oriented sleeve 200 in the vert ical installat ion direct ion V. For example, the monopile 400 may be lowered using a crane of the heavy lifting vessel.

During the insertion, the monopile 400 may deviate from its intended orientation, i.e. the vertical installation direction V. For example, due to vessel movements caused by waves and water currents. In principle, the template will correct for this deviation and force the monopile into sleeve direction S that coincides with the vertical installation direction V. However, if the lateral deviations of the monopile are becoming too large, the forces exerted on the sleeve may exceed a predetermined threshold. Therefore, the installation template 100 is adapted to temporarily reorient the sleeve direction S when the lateral force component exerted on the sleeve 200 is too great, for example when a threshold value is exceeded relative to the lateral force component. If the forces due to the deviations of the monopile are becoming too large on the template, the positioning members 330, e.g. hydraulic cylinders, may make a damping motion by allowing the sleeve to follow the monopile motion. Thus, a relatively large movement of the monopile 400 in the sleeve 200 will be able to be damped and make it possible to install the monopile 400 in the vertical installation direction V. Once the monopile is completely inserted into the sleeve and is touching the seabed, the sleeve maintains its vertical position. The heavy lift crane is now disconnected from the monopile and picks up a hammering tool. The hammer drives down the monopile into the seabed, while the sleeve is maintaining the vertical position.

Figure 5D shows the template 100 after installing the monopile 400 in the underwater ground formation 500 during the retrieval of the template 100. This template may be reused for installing another monopile.

If this other monopile is of a different type, or is installed in a different environment, it is desirable to adjust the template 100 for this purpose. For example, the position of the feet 350 relative to the base may be adjusted according to the properties of the seabed 510. In addition, it is also possible to adjust the sleeve, for example, the height of the sleeve 200 can be adjusted to the water level by means of the modular sleeved parts 220, or another sleeve can be used in combination with the same assembly. Preferably, the height of the sleeve is adjusted to rise above the water level. Other alternatives and equivalent embodiments of the present invention are conceivable within the idea of the invention, as will be clear to the person skilled in the art. The scope of the invention is limited only by the appended claims.

List of reference signs

100. Template

200. Sleeve

210. Main part

220. Modular Sleeve part

230. Top part

240. Hinge arm

300. Support Assembly

310. Annular Base

320. Support Frame

330. Positioning member

340. Spherical hinge surfaces

350. Feet 400. Monopile

500. Underwater ground formation

510. Seabed

600. Water formation

610. Water surface

O. Support direction

R. Rotation point

S. Sleeve direction

V. Vertical installation direction

Claims

1. Offshore installation template (100) for installing a monopile (400) in an underwater ground formation (500), comprising:

- a sleeve (200) with a sleeve passage extending through the sleeve in a sleeve direction (S), said sleeve passage being adapted to receive the monopile (400) and to pass the monopile (400) through the sleeve (200) in the sleeve direction (S); and

- a support assembly (300) comprising a base (310) defining a landing surface and a support frame (320) extending from the base (310),

wherein the installation template (100) comprises positioning members (330) for reorient the sleeve direction (S) relative to the landing surface, said positioning members (330) being adapted to reorient the sleeve direction (S) relative to the landing surface based on a force applied to the sleeve.

2. Offshore installation template (100) according to claim 1,

wherein the positioning members (330) are adapted to reorient the sleeve direction (S) relative to the landing surface when passing a threshold of the force applied to the sleeve.

3. Offshore installation template (100) according to claim 2,

wherein the positioning members (330) are adapted to reorient the sleeve direction (S) relative to the landing surface in the direction of the force acting on the sleeve when the threshold is exceeded, and/or

wherein the positioning members (330) are adapted to reorient the sleeve direction (S) relative to the landing surface in the direction of a vertical installation direction (V) with respect to the environment, in particular an offshore environment, when the force applied to the sleeve falls below the threshold or a second threshold that is less than the threshold, and preferably maintained below that threshold during a predetermined time.

4. Offshore installation template (100) according to any one of the preceding claims, wherein the positioning members (330) extend between the support frame (320) of the support assembly (300) and the sleeve (200), preferably at least at least three positioning members (331, 332, 333, 334) are rotationally symmetrical in an orientation plane.

5. Offshore installation template (100) according to any one of the preceding claims, wherein the positioning members (330) are hydraulic cylinders arranged to adapt a pressure level of the cylinders based on the force applied to the sleeve, in particular upon passing a predetermined threshold value.

6. Offshore installation template (100) according to any one of the preceding claims, wherein the installation template (100) comprises a sensor, said sensor being adapted to determine a parameter related to a force exerted on the sleeve.

7. Offshore installation template (100) according to any one of the preceding claims, in which the sleeve (200) and the support assembly (300) together comprise spherical hinge elements which together define a ball and a socket of a ball joint and allow a rotation of the sleeve with respect to the support assembly ( 300) around a rotation point (R).

8. Offshore installation template (100) according to claim 7, wherein the socket is formed by hinge elements provided on the sleeve (200) and the ball is formed by hinge elements provided on the support assembly (300).

9. Offshore installation template (100) according to claim 8, said spherical hinge elements of the sleeve being formed by a plurality of hinge arms (240) which are rotationally symmetrically provided on an outer surface of the sleeve (200); and said spherical hinge members of the support assembly being formed by a plurality of spherical surfaces (340) that are rotationally symmetrically provided on the base (310) of the support assembly (300).

10. Offshore installation template (100) according to one of claims 7 - 9, wherein the rotation point (R) of the spherical hinge coincides with a point of a passage opening of the base (310), said passage opening being provided for the passage of the monopile (400) into the underwater ground formation (500).

11. Offshore installation template (100) according to any one of the preceding claims, wherein the support assembly (300) comprises at least one foot (350) for stabilizing the position of the support assembly (300) relative to the seabed of the underwater ground formation (500).

12. Offshore installation template (100) according to one of the preceding claims, wherein the dimension of the sleeve (200) in the sleeve direction (S) is adjustable.

13. Offshore installation template ( 100) according to claim 12, wherein the sleeve (200) is modularly arranged by means of a main part (210) and a top part (230) connected thereto.

14. Offshore installation template (100) according to claim 13, wherein the top part (230) is connected to the main part (210) by means of at least one modular part (220).

15. Use of an offshore installation template (100) according to one of claims 1 - 14 in an offshore environment comprising a ground formation (500) with a seabed (510) and a water formation (600) with a water surface (610),

wherein the base (310) of the support assembly (300) is located on the seabed (510) of the ground formation (500), and

wherein the sleeve (200) extends through the water surface (610) of the water formation (600).

16. Method for installing a monopile (400) in an underwater ground formation (500) by means of an installation template (100), comprising the steps of:

— providing a base (310) of the installation template (100) on a seabed (510) of the underwater ground formation (500);

- introducing the monopile (400) into a sleeve passage extending through a sleeve (200) of the installation template (100); and

- preferably when a threshold value of a force applied to the sleeve (200) is passed, reorienting a sleeve direction (S) relative to a landing surface of the base (310) adjoining the seabed based on a force applied to the sleeve (200).

17. Method for installing a monopile (400) according to claim 16, comprising, prior to the step of introducing the monopile, the step of:

- orienting the sleeve direction (S) relative to the landing surface by means of positioning members (330).

18. Method for installing a monopile (400) according to claim 16 or claim 17 by means of an offshore installation template (100) according to any one of the claims 1-14.